kernel/power/wakelock.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * kernel/power/wakelock.c
   4  *
   5  * User space wakeup sources support.
   6  *
   7  * Copyright (C) 2012 Rafael J. Wysocki <rjw@sisk.pl>
   8  *
   9  * This code is based on the analogous interface allowing user space to
  10  * manipulate wakelocks on Android.
  11  */
  12
  13 #include <linux/capability.h>
  14 #include <linux/ctype.h>
  15 #include <linux/device.h>
  16 #include <linux/err.h>
  17 #include <linux/hrtimer.h>
  18 #include <linux/list.h>
  19 #include <linux/rbtree.h>
  20 #include <linux/slab.h>
  21 #include <linux/workqueue.h>
  22
  23 #include "power.h"
  24
  25 static DEFINE_MUTEX(wakelocks_lock);
  26
  27 struct wakelock {
  28         char                    *name;
  29         struct rb_node          node;
  30         struct wakeup_source    *ws;
  31 #ifdef CONFIG_PM_WAKELOCKS_GC
  32         struct list_head        lru;
  33 #endif
  34 };
  35
  36 static struct rb_root wakelocks_tree = RB_ROOT;
  37
  38 ssize_t pm_show_wakelocks(char *buf, bool show_active)
  39 {
  40         struct rb_node *node;
  41         struct wakelock *wl;
  42         int len = 0;
  43
  44         mutex_lock(&wakelocks_lock);
  45
  46         for (node = rb_first(&wakelocks_tree); node; node = rb_next(node)) {
  47                 wl = rb_entry(node, struct wakelock, node);
  48                 if (wl->ws->active == show_active)
  49                         len += sysfs_emit_at(buf, len, "%s ", wl->name);
  50         }
  51
  52         len += sysfs_emit_at(buf, len, "\n");
  53
  54         mutex_unlock(&wakelocks_lock);
  55         return len;
  56 }
  57
  58 #if CONFIG_PM_WAKELOCKS_LIMIT > 0
  59 static unsigned int number_of_wakelocks;
  60
  61 static inline bool wakelocks_limit_exceeded(void)
  62 {
  63         return number_of_wakelocks > CONFIG_PM_WAKELOCKS_LIMIT;
  64 }
  65
  66 static inline void increment_wakelocks_number(void)
  67 {
  68         number_of_wakelocks++;
  69 }
  70
  71 static inline void decrement_wakelocks_number(void)
  72 {
  73         number_of_wakelocks--;
  74 }
  75 #else /* CONFIG_PM_WAKELOCKS_LIMIT = 0 */
  76 static inline bool wakelocks_limit_exceeded(void) { return false; }
  77 static inline void increment_wakelocks_number(void) {}
  78 static inline void decrement_wakelocks_number(void) {}
  79 #endif /* CONFIG_PM_WAKELOCKS_LIMIT */
  80
  81 #ifdef CONFIG_PM_WAKELOCKS_GC
  82 #define WL_GC_COUNT_MAX 100
  83 #define WL_GC_TIME_SEC  300
  84
  85 static void __wakelocks_gc(struct work_struct *work);
  86 static LIST_HEAD(wakelocks_lru_list);
  87 static DECLARE_WORK(wakelock_work, __wakelocks_gc);
  88 static unsigned int wakelocks_gc_count;
  89
  90 static inline void wakelocks_lru_add(struct wakelock *wl)
  91 {
  92         list_add(&wl->lru, &wakelocks_lru_list);
  93 }
  94
  95 static inline void wakelocks_lru_most_recent(struct wakelock *wl)
  96 {
  97         list_move(&wl->lru, &wakelocks_lru_list);
  98 }
  99
 100 static void __wakelocks_gc(struct work_struct *work)
 101 {
 102         struct wakelock *wl, *aux;
 103         ktime_t now;
 104
 105         mutex_lock(&wakelocks_lock);
 106
 107         now = ktime_get();
 108         list_for_each_entry_safe_reverse(wl, aux, &wakelocks_lru_list, lru) {
 109                 u64 idle_time_ns;
 110                 bool active;
 111
 112                 spin_lock_irq(&wl->ws->lock);
 113                 idle_time_ns = ktime_to_ns(ktime_sub(now, wl->ws->last_time));
 114                 active = wl->ws->active;
 115                 spin_unlock_irq(&wl->ws->lock);
 116
 117                 if (idle_time_ns < ((u64)WL_GC_TIME_SEC * NSEC_PER_SEC))
 118                         break;
 119
 120                 if (!active) {
 121                         wakeup_source_unregister(wl->ws);
 122                         rb_erase(&wl->node, &wakelocks_tree);
 123                         list_del(&wl->lru);
 124                         kfree(wl->name);
 125                         kfree(wl);
 126                         decrement_wakelocks_number();
 127                 }
 128         }
 129         wakelocks_gc_count = 0;
 130
 131         mutex_unlock(&wakelocks_lock);
 132 }
 133
 134 static void wakelocks_gc(void)
 135 {
 136         if (++wakelocks_gc_count <= WL_GC_COUNT_MAX)
 137                 return;
 138
 139         schedule_work(&wakelock_work);
 140 }
 141 #else /* !CONFIG_PM_WAKELOCKS_GC */
 142 static inline void wakelocks_lru_add(struct wakelock *wl) {}
 143 static inline void wakelocks_lru_most_recent(struct wakelock *wl) {}
 144 static inline void wakelocks_gc(void) {}
 145 #endif /* !CONFIG_PM_WAKELOCKS_GC */
 146
 147 static struct wakelock *wakelock_lookup_add(const char *name, size_t len,
 148                                             bool add_if_not_found)
 149 {
 150         struct rb_node **node = &wakelocks_tree.rb_node;
 151         struct rb_node *parent = *node;
 152         struct wakelock *wl;
 153
 154         while (*node) {
 155                 int diff;
 156
 157                 parent = *node;
 158                 wl = rb_entry(*node, struct wakelock, node);
 159                 diff = strncmp(name, wl->name, len);
 160                 if (diff == 0) {
 161                         if (wl->name[len])
 162                                 diff = -1;
 163                         else
 164                                 return wl;
 165                 }
 166                 if (diff < 0)
 167                         node = &(*node)->rb_left;
 168                 else
 169                         node = &(*node)->rb_right;
 170         }
 171         if (!add_if_not_found)
 172                 return ERR_PTR(-EINVAL);
 173
 174         if (wakelocks_limit_exceeded())
 175                 return ERR_PTR(-ENOSPC);
 176
 177         /* Not found, we have to add a new one. */
 178         wl = kzalloc(sizeof(*wl), GFP_KERNEL);
 179         if (!wl)
 180                 return ERR_PTR(-ENOMEM);
 181
 182         wl->name = kstrndup(name, len, GFP_KERNEL);
 183         if (!wl->name) {
 184                 kfree(wl);
 185                 return ERR_PTR(-ENOMEM);
 186         }
 187
 188         wl->ws = wakeup_source_register(NULL, wl->name);
 189         if (!wl->ws) {
 190                 kfree(wl->name);
 191                 kfree(wl);
 192                 return ERR_PTR(-ENOMEM);
 193         }
 194         wl->ws->last_time = ktime_get();
 195
 196         rb_link_node(&wl->node, parent, node);
 197         rb_insert_color(&wl->node, &wakelocks_tree);
 198         wakelocks_lru_add(wl);
 199         increment_wakelocks_number();
 200         return wl;
 201 }
 202
 203 int pm_wake_lock(const char *buf)
 204 {
 205         const char *str = buf;
 206         struct wakelock *wl;
 207         u64 timeout_ns = 0;
 208         size_t len;
 209         int ret = 0;
 210
 211         if (!capable(CAP_BLOCK_SUSPEND))
 212                 return -EPERM;
 213
 214         while (*str && !isspace(*str))
 215                 str++;
 216
 217         len = str - buf;
 218         if (!len)
 219                 return -EINVAL;
 220
 221         if (*str && *str != '\n') {
 222                 /* Find out if there's a valid timeout string appended. */
 223                 ret = kstrtou64(skip_spaces(str), 10, &timeout_ns);
 224                 if (ret)
 225                         return -EINVAL;
 226         }
 227
 228         mutex_lock(&wakelocks_lock);
 229
 230         wl = wakelock_lookup_add(buf, len, true);
 231         if (IS_ERR(wl)) {
 232                 ret = PTR_ERR(wl);
 233                 goto out;
 234         }
 235         if (timeout_ns) {
 236                 u64 timeout_ms = timeout_ns + NSEC_PER_MSEC - 1;
 237
 238                 do_div(timeout_ms, NSEC_PER_MSEC);
 239                 __pm_wakeup_event(wl->ws, timeout_ms);
 240         } else {
 241                 __pm_stay_awake(wl->ws);
 242         }
 243
 244         wakelocks_lru_most_recent(wl);
 245
 246  out:
 247         mutex_unlock(&wakelocks_lock);
 248         return ret;
 249 }
 250
 251 int pm_wake_unlock(const char *buf)
 252 {
 253         struct wakelock *wl;
 254         size_t len;
 255         int ret = 0;
 256
 257         if (!capable(CAP_BLOCK_SUSPEND))
 258                 return -EPERM;
 259
 260         len = strlen(buf);
 261         if (!len)
 262                 return -EINVAL;
 263
 264         if (buf[len-1] == '\n')
 265                 len--;
 266
 267         if (!len)
 268                 return -EINVAL;
 269
 270         mutex_lock(&wakelocks_lock);
 271
 272         wl = wakelock_lookup_add(buf, len, false);
 273         if (IS_ERR(wl)) {
 274                 ret = PTR_ERR(wl);
 275                 goto out;
 276         }
 277         __pm_relax(wl->ws);
 278
 279         wakelocks_lru_most_recent(wl);
 280         wakelocks_gc();
 281
 282  out:
 283         mutex_unlock(&wakelocks_lock);
 284         return ret;
 285 }